Neurofibromatosis type 2 tumor suppressor protein is expressed in oligodendrocytes and regulates cell proliferation and process formation

PLoS One. 2018 May 1;13(5):e0196726. doi: 10.1371/journal.pone.0196726. eCollection 2018.

Abstract

The neurofibromatosis type 2 (NF2) tumor suppressor protein Merlin functions as a negative regulator of cell growth and actin dynamics in different cell types amongst which Schwann cells have been extensively studied. In contrast, the presence and the role of Merlin in oligodendrocytes, the myelin forming cells within the CNS, have not been elucidated. In this work, we demonstrate that Merlin immunoreactivity was broadly distributed in the white matter throughout the central nervous system. Following Merlin expression during development in the cerebellum, Merlin could be detected in the cerebellar white matter tract at early postnatal stages as shown by its co-localization with Olig2-positive cells as well as in adult brain sections where it was aligned with myelin basic protein containing fibers. This suggests that Merlin is expressed in immature and mature oligodendrocytes. Expression levels of Merlin were low in oligodendrocytes as compared to astrocytes and neurons throughout development. Expression of Merlin in oligodendroglia was further supported by its identification in either immortalized cell lines of oligodendroglial origin or in primary oligodendrocyte cultures. In these cultures, the two main splice variants of Nf2 could be detected. Merlin was localized in clusters within the nuclei and in the cytoplasm. Overexpressing Merlin in oligodendrocyte cell lines strengthened reduced impedance in XCELLigence measurements and Ki67 stainings in cultures over time. In addition, the initiation and elongation of cellular projections were reduced by Merlin overexpression. Consistently, cell migration was retarded in scratch assays done on Nf2-transfected oligodendrocyte cell lines. These data suggest that Merlin actively modulates process outgrowth and migration in oligodendrocytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / metabolism
  • Cell Line
  • Cell Movement / physiology
  • Cell Nucleus / metabolism
  • Cell Proliferation / physiology*
  • Central Nervous System / metabolism
  • Cytoplasm / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Nerve Tissue Proteins / metabolism
  • Neurofibromatosis 2 / metabolism*
  • Neurofibromin 2 / metabolism*
  • Neurogenesis / physiology
  • Neurons / metabolism
  • Oligodendroglia / metabolism*
  • Schwann Cells / metabolism
  • Transfection / methods

Substances

  • Nerve Tissue Proteins
  • Neurofibromin 2

Grant support

This work was supported by the Alexander von Humboldt foundation (https://www.humboldt-foundation.de/web/start.html, HERMES to AT), and by BONFOR (http://www.ukb.uni-bonn.de/quick2web/internet/internet.nsf/vwUNIDLookup/B72A5EAAF5CFF627C1257658002584DA, O-167.0017 to SLB). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.